Applicator heads are used in conjunction with various compounds to treat the surfaces of a wide range of materials including paint, metal composites and plastics. The compound is normally in the form of a paste or liquid. The heads typically consist of a cylindrical pad with a hub element fixed to one end face for attaching the pad to the shaft of a drive unit. The pad material is selected according to the material to be treated or the particular stage of a series of treatments to the same surface.
In one known applicator head configuration, the pad is permanently fixed to the hub element and it is necessary to replace the complete head once the pad is worn out. Another form of head incorporates a replaceable pad arrangement, in which a "hook-and-loop" type fastening system is used with components disposed on opposing planar faces of the pad and the hub element. Thus, once the pad had exceeded its useful life, it alone needs to be replaced, without also requiring a new hub element. However, with this arrangement it is difficult to ensure that the hub element is fixed coaxially against the pad, with any eccentricity leading to increased vibration and wear.